What impacts ability for fear spell to stick?

[Hoggen]

I only played a wizard in classic. The resists were enough to make baby Jeebus weep. I remember root being resisted three and four times in a row. I remember full resists of ice, fire, you name it, on blue mobs. Classic resists just plain sucked for certain classes/spells. The only "unresistable" spells seemed to be lifetaps. That's why necros were so desirable on dragon raids.